check minimum VM version when setting VM snapshots

Some Hyper-V operations require a minimum VM version in order to succeed.
For example, Production Checkpoints are supported on VM Versions 6.2 and
newer.

Clustering Hyper-V compute nodes may change the list of supported VM
versions list and the default VM version on that host.

https://docs.microsoft.com/en-us/windows-server/virtualization/hyper-v/deploy/upgrade-virtual-machine-version-in-hyper-v-on-windows-or-windows-server

Partial-Bug: #1707605
Change-Id: Iac795f570649ce28847b88c5a21e575daefefc49

os_win/_utils.py

@@ -15,6 +15,8 @@
 #    under the License.
 
 import ctypes
+import inspect
+from pkg_resources import parse_version
 import textwrap
 import time
 import types
@@ -29,6 +31,7 @@ from oslo_utils import excutils
 from oslo_utils import reflection
 import six
 
+from os_win import constants
 from os_win import exceptions
 
 
@@ -256,3 +259,43 @@ def hex_str_to_byte_array(string):
 
 def byte_array_to_hex_str(byte_aray):
     return ''.join('{:02X}'.format(b) for b in byte_aray)
+
+
+def required_vm_version(min_version=constants.VM_VERSION_5_0,
+                        max_version=constants.VM_VERSION_254_0):
+    """Ensures that the wrapped method's VM meets the version requirements.
+
+    Some Hyper-V operations require a minimum VM version in order to succeed.
+    For example, Production Checkpoints are supported on VM Versions 6.2 and
+    newer.
+
+    Clustering Hyper-V compute nodes may change the list of supported VM
+    versions list and the default VM version on that host.
+
+    :param min_version: string, the VM's minimum version required for the
+        operation to succeed.
+    :param max_version: string, the VM's maximum version required for the
+        operation to succeed.
+    :raises exceptions.InvalidVMVersion: if the VM's version does not meet the
+        given requirements.
+    """
+
+    def wrapper(func):
+        def inner(*args, **kwargs):
+            all_args = inspect.getcallargs(func, *args, **kwargs)
+            vmsettings = all_args['vmsettings']
+
+            # NOTE(claudiub): VMs on Windows / Hyper-V Server 2012 do not have
+            # a Version field, but they are 4.0.
+            vm_version_str = getattr(vmsettings, 'Version', '4.0')
+            vm_version = parse_version(vm_version_str)
+            if (vm_version >= parse_version(min_version) and
+                    vm_version <= parse_version(max_version)):
+                return func(*args, **kwargs)
+
+            raise exceptions.InvalidVMVersion(
+                vm_name=vmsettings.ElementName, version=vm_version_str,
+                min_version=min_version, max_version=max_version)
+
+        return inner
+    return wrapper

os_win/constants.py

@@ -211,6 +211,11 @@ VM_SNAPSHOT_TYPE_PROD_FALLBACK = 3
 VM_SNAPSHOT_TYPE_PROD_ENFORCED = 4
 VM_SNAPSHOT_TYPE_STANDARD = 5
 
+VM_VERSION_5_0 = '5.0'
+VM_VERSION_6_2 = '6.2'
+VM_VERSION_8_0 = '8.0'
+VM_VERSION_254_0 = '254.0'
+
 DEFAULT_WMI_EVENT_TIMEOUT_MS = 2000
 
 SCSI_UID_SCSI_NAME_STRING = 8

os_win/exceptions.py

@@ -104,6 +104,12 @@ class InvalidParameterValue(Invalid):
                 "%(param_name)s=%(param_value)s")
 
 
+class InvalidVMVersion(Invalid):
+    msg_fmt = _("VM '%(vm_name)s' has an invalid version for this operation: "
+                "%(version)s. Version is expected to be between: "
+                "%(min_version)s and %(max_version)s.")
+
+
 class SMBException(OSWinException):
     pass
 

os_win/tests/unit/test_utils.py

@@ -23,6 +23,7 @@ import mock
 from oslotest import base
 
 from os_win import _utils
+from os_win import constants
 from os_win import exceptions
 
 
@@ -286,3 +287,20 @@ class UtilsTestCase(base.BaseTestCase):
         expected_string = '000102'
 
         self.assertEqual(expected_string, resulted_string)
+
+    def test_required_vm_version(self):
+        @_utils.required_vm_version()
+        def foo(bar, vmsettings):
+            pass
+
+        mock_vmsettings = mock.Mock()
+
+        for good_version in [constants.VM_VERSION_5_0,
+                             constants.VM_VERSION_254_0]:
+            mock_vmsettings.Version = good_version
+            foo(mock.sentinel.bar, mock_vmsettings)
+
+        for bad_version in ['4.99', '254.1']:
+            mock_vmsettings.Version = bad_version
+            self.assertRaises(exceptions.InvalidVMVersion, foo,
+                              mock.sentinel.bar, mock_vmsettings)

os_win/tests/unit/utils/compute/test_vmutils10.py

@@ -351,7 +351,7 @@ class VMUtils10TestCase(test_base.OsWinBaseTestCase):
             mock_get_element_associated_class.return_value)
 
     def test_set_snapshot_type(self):
-        vmsettings = mock.Mock()
+        vmsettings = mock.Mock(Version='6.2')
 
         self._vmutils._set_vm_snapshot_type(
             vmsettings, mock.sentinel.snapshot_type)

os_win/utils/compute/vmutils.py

@@ -296,7 +296,7 @@ class VMUtils(baseutils.BaseUtilsVirt):
                   vcpus_per_numa_node, limit_cpu_features, dynamic_mem_ratio,
                   configuration_root_dir=None, snapshot_dir=None,
                   host_shutdown_action=None, vnuma_enabled=None,
-                  snapshot_type=constants.VM_SNAPSHOT_TYPE_PROD_FALLBACK,
+                  snapshot_type=None,
                   is_planned_vm=False):
         vmsetting = self._lookup_vm_check(vm_name, for_update=True)
 
@@ -318,6 +318,7 @@ class VMUtils(baseutils.BaseUtilsVirt):
         self._set_vm_vcpus(vmsetting, vcpus_num, vcpus_per_numa_node,
                            limit_cpu_features)
 
+        if snapshot_type:
             self._set_vm_snapshot_type(vmsetting, snapshot_type)
 
         self._modify_virtual_system(vmsetting)

os_win/utils/compute/vmutils10.py

@@ -19,6 +19,7 @@ from oslo_log import log as logging
 import six
 
 from os_win._i18n import _
+from os_win import _utils
 from os_win import constants
 from os_win import exceptions
 from os_win.utils import _wqlutils
@@ -289,6 +290,7 @@ class VMUtils10(vmutils.VMUtils):
         if pci_sds:
             self._jobutils.remove_multiple_virt_resources(pci_sds)
 
+    @_utils.required_vm_version(min_version=constants.VM_VERSION_6_2)
     def _set_vm_snapshot_type(self, vmsettings, snapshot_type):
         # We expect the caller to actually push the vmsettings update.
         vmsettings.UserSnapshotType = snapshot_type